- 1(current)
Q. No.A semiconductor is known to have an electron concentration of \(8\times 10^{13}~\text{cm}^{-3},\) and a hole concentration of \(5\times 10^{2}~\text{cm}^{-3}.\) The semiconductor is:
| 1. | \(\mathrm{n}\text-\)type | 2. | \(\mathrm{p}\text-\)type |
| 3. | intrinsic | 4. | insulator |
Subtopic: Â Types of Semiconductors |
 87%
From NCERT
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If a small amount of aluminium is added to the silicon crystal:
| 1. | its resistance decreases. |
| 2. | it becomes a \(\mathrm{p\text-}\)type semiconductor. |
| 3. | there will be fewer free electrons than holes in the semiconductor. |
| 4. | All of these are correct. |
Subtopic: Â Types of Semiconductors |
 75%
From NCERT
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Pure \(\mathrm{Si}\) at \(500~\text K\) has an equal number of electrons \((n_i)\) and the hole \((n_h)\) concentration of \(1.5\times10^{16}~\text{m}^{-3}.\) Doping by indium increases the hole concentration \(n_h\) to \(4.5\times 10^{22}~\text{m}^{-3}.\) The doped semiconductor is of:
| 1. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=5\times10^{22}~\text{m}^{-3}\) |
| 2. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=2.5\times10^{23}~\text{m}^{-3}\) |
| 3. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=2.5\times10^{10}~\text{m}^{-3}\) |
| 4. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=5\times10^{9}~\text{m}^{-3}\) |
Subtopic: Â Types of Semiconductors |
 71%
From NCERT
NEET - 2011
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A \(Ge\) specimen is doped with \(Al\). The concentration of acceptor atoms is \(\sim10^{21}~\text{atoms/m}^3\). Given that the intrinsic concentration of electron hole pairs is \(\sim10^{19}/\text{m}^3\) the concentration of electrons in the specimen is:
| 1. | \(10^{17} / \text{m}^3 \) | 2. | \(10^{15} / \text{m}^3 \) |
| 3. | \(10^4 / \text{m}^3 \) | 4. | \(10^2 / \text{m}^3\) |
Subtopic: Â Types of Semiconductors |
 72%
From NCERT
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In a semiconducting material, the mobilities of electrons and holes are \(\mu_e\) and \(\mu_{h}\) respectively. Which of the following is true?
1. \(\mu_{e} > \mu _{h}\)
2. \(\mu_{e} < \mu _{h}\)
3. \(\mu_{e} = \mu _{h}\)
4. \(\mu_{e} <0; ~\mu _{h}>0\)
Subtopic: Â Types of Semiconductors |
 69%
From NCERT
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The net charges on -type semiconductor and -type semiconductor are, respectively:
| 1. | Positive, negative | 2. | Negative, positive |
| 3. | Positive, positive | 4. | Zero, zero |
Subtopic: Â Types of Semiconductors |
 70%
From NCERT
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- 1(current)
Q. No.
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